Ureteral stent with conforming retention structure

ABSTRACT

A ureteral stent includes an elongate member defining an axis and having a proximal end portion and a distal end portion. A first extension member and a second extension member extend from the proximal end portion and each include a first portion, a second portion, a third portion and an end portion. In an unconstrained configuration, the first portion is arcuate and extends away from the axis, the second portion extends from the first portion in a distal direction, and the third portion extends from the second portion in a direction away from the axis. In the unconstrained configuration, the end portions of the first and second extension members are spaced apart from each other sufficiently, and the first extension member and the second extension member are sufficiently rigid, to collectively help retain at least a portion of the ureteral stent within a bladder of a patient.

BACKGROUND

The disclosed invention relates generally to a medical device and moreparticularly to a ureteral stent having a conforming retention structureto provide improved patient comfort.

Known ureteral stents are typically placed within a urinary tract of apatient such that one end portion of the ureteral stent is located ineither a kidney or a ureter of the patient and another end portion ofthe ureteral stent is located in a bladder of the patient. Some knownureteral stents include retention members configured to help retain theureteral stent in position within the patient. Known ureteral stents aretypically positioned within the urinary tract of the patient by placinga guidewire within the patient, sliding the ureteral stent on theguidewire, and then forcing the ureteral stent along the guidewire intoa desired position within the patient using a push cannula. Suchureteral stents are often removed from the patient by pulling theureteral stent from the urinary tract of the patient.

Known ureteral stents often cause discomfort to the patient once theureteral stents are positioned within the body due to the size and massof the retention members. For example, some ureteral stents include acurled end portion that may be positioned in a bladder of a patient tohelp retain the ureteral stent in place within the patient. The largemass of the curled retention structure does not easily conform to thebladder when the bladder is emptied or collapsed, resulting in patientdiscomfort. Further discomfort can also result when the ureteral stentis removed from a patient due to the configuration of the retentionmember.

Thus, there is a need for a ureteral stent having a retention portionthat distributes the mass of the retention structure within the bladderand conforms to the shape of the bladder walls to help reduce pain anddiscomfort to the patient.

SUMMARY OF THE INVENTION

A ureteral stent includes an elongate member defining an axis and havinga proximal end portion and a distal end portion. A first extensionmember and a second extension member extend from the proximal endportion of the elongate member. The first extension member and thesecond extension member each include a first portion, a second portion,a third portion and an end portion. In an unconstrained configuration,the first portion is arcuate and extends away from the axis defined bythe elongate member, the second portion extends from the first portionin a distal direction, and the third portion extends from the secondportion in a direction away from the axis defined by the elongatemember. In the unconstrained configuration, the end portion of the firstextension member and the end portion of the second extension member arespaced apart from each other sufficiently, and the first extensionmember and the second extension member are sufficiently rigid, tocollectively help retain at least a portion of the ureteral stent withina bladder of a patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements. For example item 100 is identical orfunctionally similar to item 100A.

FIG. 1 is a schematic illustration of a ureteral stent according to anembodiment of the invention.

FIG. 2A is side view of a ureteral stent according to an embodiment ofthe invention shown positioned in a kidney, ureter and bladder of apatient.

FIG. 2B is a bottom view of the ureteral stent shown in FIG. 2A.

FIG. 3A is a side view of a portion of a ureteral stent according to anembodiment of the invention.

FIG. 3B is a side view of a portion of a ureteral stent according to anembodiment of the invention.

FIGS. 3C-3F are side views of extension members according to severalembodiments of the invention.

FIG. 4 is a side view of a portion of the ureteral stent of FIG. 3Ashown in an unconstrained configuration.

FIG. 5A is a side view of the portion of the ureteral stent of FIGS. 3Aand 4 shown in a constrained configuration.

FIG. 5B is a cross-sectional view taken along line 5B-5B in FIG. 5A.

FIG. 5C is a cross-sectional view taken along line 5C-5C in FIG. 5A

FIG. 6 is a side view of a ureteral stent according to anotherembodiment of the invention shown positioned in a ureter and bladder ofa patient.

FIG. 7A is a side view of a portion of a ureteral stent according to anembodiment of the invention.

FIG. 7B is a side view of a portion of a ureteral stent according to anembodiment of the invention.

FIGS. 7C-7G are side views of extension members according to severalembodiments of the invention.

FIG. 8A is a side view of a ureteral stent according to anotherembodiment of the invention.

FIG. 8B-8E are side views of a portion of a ureteral stent according toseveral embodiments of the invention.

FIG. 9A is a side view of a portion of a ureteral stent according to anembodiment of the invention shown in a constrained configuration.

FIG. 9B is a side view of a portion of the ureteral stent of FIG. 9Ashown in an unconstrained configuration.

FIG. 9C is a cross-sectional view taken along line 9C-9C in FIG. 9B.

FIGS. 9D and 9E are cross-sectional views taken along lines 9D-9D and9E-9E, respectively, in FIG. 9A.

DETAILED DESCRIPTION

FIG. 1 is a schematic illustration of a ureteral stent 100 disposedwithin a urinary tract of a patient. Specifically, the ureteral stent100 is placed or otherwise implanted into the urinary tract of a patientsuch that the ureteral stent 100 extends through the ureter U, from thekidney K of the patient to the bladder B of the patient. The ureteralstent 100 is configured to help facilitate the movement of fluid withina urinary tract of a patient.

The ureteral stent 100 includes an elongate member 102 having a distalend portion 104, a proximal end portion 106, and a medial portion 108. Aretention portion 110 extends from the proximal end portion 106 of theelongate member 102. Similarly, a retention portion 112 extends from thedistal end portion 104 of the elongate member 102. The elongate member102 defines an axis A and a lumen (not shown in FIG. 1). The lumen mayextend from the distal end portion 104 to the proximal end portion 106of the elongate member 102. The elongate member 102 further defines anopening (not shown in FIG. 1) on the proximal end portion of theelongate member 102 that communicates with the lumen. In otherembodiments, the lumen may not extend from the distal end portion 104 tothe proximal end portion 106. Rather, the lumen may only extend througha portion of the elongate member 102. In yet another embodiment, theelongate member 102 does not include an opening on the proximal endportion that communicates with the lumen.

The retention portion 112 extends from the distal end portion 104 of theelongate member 102 and is configured to be placed in the kidney K ofthe patient. The retention portion 112 is configured to help preventmigration of the ureteral stent 100 downwardly toward the bladder B.Accordingly, the retention member 112 is configured to help retain atleast a portion of the ureteral stent 100 within the kidney K of thepatient. Retention portion 112 may be configured in a variety ofdifferent shapes and sizes. For example, the retention portion 112 mayinclude a coil portion or a loop portion.

The retention portion 110 extends from the proximal end portion 106 ofthe elongate member 102 and is configured to be placed within thebladder B of the patient. The retention portion 106 is configured tohelp prevent migration of the ureteral stent 100 upwardly toward thekidney K of the patient. Accordingly, the retention portion 110 isconfigured to help retain at least a portion of the ureteral stent 100within the bladder B of the patient. Retention portion 110 includes oneor more extension members 114 that extend from the proximal end portion106 of the elongate member 102. In the embodiment shown in FIG. 1,retention portion 110 includes two extension members 114. Each extensionmember 114 includes an end portion 118. Each of the extension members114 may be formed monolithically with the elongate member 102.Alternatively, the extension members 114 may be coupled to the elongatemember 102 such as, for example, via an adhesive or a mechanicalcoupling. Although two extension members are illustrated in FIG. 1, itshould be understood that any number of extension members can be used aswill be shown in other embodiments.

Extension members 114 may be configured in a variety of different shapesand sizes, and are flexible yet sufficiently rigid to collectively helpretain at least a portion of the ureteral stent 100 within the bladder Bof the patient. The extension members 114 are configurable between anunconstrained configuration and a constrained configuration. In theunconstrained configuration, the end portions 118 of the extensionmembers 114 are spaced apart from each other such that the distancebetween at least two extension members 114 is greater than a ureterentrance 120. Specifically, one of the extension members 114 isconfigured to contact a bladder wall of the patient at a first contactlocation 122 and the other extension member 114 is configured to contactthe bladder wall of the patient at a second contact location 124. Thefirst contact location 122 and the second contact location 124 aredisposed at a spaced distance from the ureter entrance 120 of thepatient. The extension members 114 are configurable to the constrainedconfiguration by urging the end portions 118 of the extension members114 such that the extension members 114 are positioned substantiallyadjacent each other, which will be discussed in more detail below.

Although the ureteral stent 100 is illustrated and described as beingconfigured to extend from the kidney K of the patient to the bladder Bof the patient, it is not necessary that ureteral stent 100 beconfigured to extend from the kidney K to the bladder B. For example, inanother embodiment, the ureteral stent is configured to extend from theureter U of the patient to a location within the bladder B of thepatient.

In one embodiment, ureteral stent 100 is implanted into the urinarytract of the patient by inserting the stent 100 into the patienttransuretherally. For example, a guidewire may be placed within theurinary tract of the patient. Subsequently, the ureteral stent 100 maybe placed on the guidewire and forced into a desired position within theurinary tract of the patient such as via a pusher device. In anotherembodiment, ureteral stent 100 is implanted into the urinary tract ofthe patient by inserting the stent 100 into the patient transdermally orpercutaneously.

The ureteral stent 100 may be formed from a number of differentbiocompatible materials. The ureteral stent 100 may consist of onematerial or may be formed, for example by extrusion, of two or morematerials along its length. For example, in one embodiment, the distalend portion 104 of the ureteral stent 100 is formed from a firstmaterial having a first durometer and the proximal end portion 106 isformed from a second material, which is softer and/or more flexible thanthe first material, having a second durometer different than the firstdurometer. Accordingly, the proximal end portion 106 may be made of asofter or more flexible material than that of the distal end portion104, and vice versa.

The ureteral stent 100 may be formed from any material or materialsknown in the art to be used in constructing ureteral stents. One subsetof biocompatible materials best suited for the ureteral stent 100exhibit at least some of the following characteristics: high tensilestrength, high retention coil strength, excellent biocompatibility andbiodurability, excellent radiopacity or fluoroscopic visibility,availability in varying durometers, and a low resistance to passage. Forexample, in one embodiment, the ureteral stent 100 is formed from apolymeric material.

FIG. 2A illustrates a ureteral stent according to one embodiment of theinvention. The ureteral stent 100A is configured to be implanted into aurinary tract of a patient such that the ureteral stent 100A extendsfrom a kidney K of the patient to a bladder B of the patient. In thisembodiment, the ureteral stent 100A includes an elongate member 102Ahaving a distal end portion 104A, a proximal end portion 106A, and amedial portion 108A. The elongate member 102A defines an axis A1. Aretention member 112A extends from the distal end portion 104A of theelongate member 102A and is configured to be placed and retained in thekidney K of the patient. A retention portion 110A extends from theproximal end portion 106A of the elongate member 102A and is configuredto be placed and retained in the bladder B of the patient. The elongatemember 102A defines a lumen 126A and an opening 128A in communicationwith the lumen 126A, as shown in FIG. 2B.

Retention portion 110A includes four extension members 114A extendingfrom the proximal end portion 106A of the elongate member 102A. Theextension members 114A each have an end portion 118A, as shown in FIGS.2A and 2B. Extension members 114A may be formed monolithically withelongate member 102A. For example, extension members 114A may be formedby slitting plastic tubing used to construct elongate member 102A with acutting device. For example, the plastic tubing may be split asdescribed in United States Patent Application Publication No.US-2004-0193092-A1, which is hereby incorporated by reference in itsentirety. The extension members 114A are then formed into a selectedshape. Splitting the elongate member 102A to form the extension members114A spreads the mass of the retention member 102A into differentregions within the bladder of the patient. The separate extensionmembers 114A conform to the shape of the bladder of the patient, therebyproviding more patient comfort. In addition, the extension members 114Aextend in a direction away from the axis A1 and the opening 128A definedby the elongate member 102A. Thus, because the extension members 114Aextend away from the axis A1 and the opening 128A, a guidewire may beeasily inserted into the lumen 126A via the opening 128A.

Specifically, the extension members 114A each include a first arcuateportion 130A extending away from the axis A1 defined by the elongatemember 102A, a second portion 132A extending in a distal direction and athird portion extending from the second portion 132A in a direction awayfrom the axis A1 defined by the elongate member 102A.

The ureteral stent may include any number of extension members 114A. Forexample, a ureteral stent 100A′ includes two extension members 114Aextending from the proximal end portion 106A of the elongate member102A, as shown in FIG. 3A. In another example, a ureteral stent 100A″includes three extension members 114A extending from the proximal endportion 106A of the elongate member 102A, as shown in FIG. 3B. Inaddition, the extension members 114A may be configured in a variety ofdifferent shapes and sizes, while still including a first arcuateportion 130A, a second portion 132A and a third portion 134A asdescribed above. Other embodiments of extension members are shown inFIGS. 3C through 3F. Specifically, extension members 114′-114″″ areshown in FIGS. 3C through 3F, respectively.

FIG. 4 illustrates a portion of stent 100A′ shown in an unconstrainedconfiguration. The extension members 114A are each configured to contacta bladder wall of the patient at a contact location that is spaced at adistance from a ureter entrance 120A of the patient. As shown in FIG. 4,a tether 136A may be coupled to end portions 118A of the extensionmembers 114A. To withdraw the ureteral stent 100A′ from the ureter of apatient, the tether 136A is pulled proximally, which urges the endportions 118A proximally and into a constrained configuration, as shownin FIG. 5A. The extension members 114A may be urged to the constrainedconfiguration sequentially or simultaneously. In addition, the ureteralstent 100A′ may be withdrawn from the ureter of a patient by urging theureteral stent 100A′ along a guidewire. In the constrainedconfiguration, the extension members 114A are positioned substantiallyadjacent each other. In other words, when the ureteral stent 100A′ is inits constrained configuration there is no more than a substantiallysmall gap between the extension members 114A. For example, in oneembodiment, when the ureteral stent is in its constrained configuration,the extension members are disposed 0.1 mm away from each other. Inanother embodiment, when the ureteral stent is in its constrainedconfiguration, the extension member are abutting each other. Inaddition, in the constrained configuration, the extension members 114Acollectively define a perimeter P1, as shown in FIG. 5C, and theelongate member 102A defines a perimeter P2, as shown in FIG. 5B. Theperimeter P2 defined by the elongate member 102A is substantially thesame size as the perimeter P1 defined collectively by the extensionmembers 114A. In some embodiments, in the constrained configuration theextension members 114A are capable of being contained within theperimeter P2 of the elongate member 102A.

FIG. 6 illustrates a ureteral stent according to another embodiment ofthe invention. Ureteral stent 100B includes an elongate member 102Bhaving a distal end portion 104B, a medial portion 108B and a proximalend portion 106B. In this embodiment, the distal end portion 104B doesnot include a retention portion. The distal end portion 104B of theelongate member 102B is configured to be positioned within a ureter U ofa patient. A retention portion 110B, similar to the retention portion110A, extends from the proximal end portion 106B of the elongate member102B. The retention portion 110B includes four extension members 114B,which are constructed substantially the same as the previous embodimentsand perform substantially the same functions as the previousembodiments. The extension members 114B each extend from the proximalend portion 106B of the elongate member 102B in a direction away from anaxis A2 defined by the elongate member 102B. The extension members 114Beach include an end portion 118B.

The extension members 114B have the same properties when positioned inan unconstrained configuration and a constrained configuration as withthe previous embodiments. For example, the end portions 118B of theextension members 114B are disposed apart from each other and contactthe bladder wall at a spaced distance from a ureter opening when theureteral stent 100B is in its unconstrained configuration. In addition,the extension members 114B may be urged into a constrained configurationin the same manner as previously described. In the constrainedconfiguration, a perimeter defined collectively by the extension members114B is substantially the same size as a perimeter defined by theelongate member 102B.

The extension members 114B differ from extension members 114A in thatthey each include a coil configuration extending in a direction awayfrom the axis A2 defined by the elongate member 102B. The coilconfiguration of each of the extension members 114B includes at leastone complete turn as shown in FIG. 6.

The ureteral stent 100B may include any number of extension members 114Bextending from the proximal end portion 106B of the elongate member102B. For example, FIG. 7A illustrates a portion of a ureteral stent100B′ having two extension members 114B extending from the proximal endportion 106B of the elongate member 102B. FIG. 7B illustrates a portionof a ureteral stent 100B″ having three extension members 114B extendingfrom the proximal end portion 106B of the elongate member 102B. Inaddition, the coil configuration of the extension members 114B may beconfigured in several different shapes and sizes. Specifically, otherembodiments of extension members 114B′-114B″″ are illustrated in FIGS.7C-7G, respectively. Extension members 114B′-114B″″ all include a coilconfiguration having at least one complete turn.

FIG. 8A illustrates a ureteral stent according to yet another embodimentof the invention. The ureteral stent 100C is configured substantiallysimilar to and performs substantially the same functions as the previousembodiments. The ureteral stent 100C includes an elongate member 102Chaving a distal end portion 104C, a medial portion 108C and a proximalend portion 106C. The ureteral stent 100C includes a retention portion112C configured to be placed in a kidney of a patient and a retentionportion 110C configured to be placed in a bladder of the patient. Theelongate member 102C defines an axis A3, a lumen (not shown in FIG. 8A),and an opening on the proximal end portion 106C of the elongate member102C (not shown in FIG. 8A) that communicates with the lumen. In oneembodiment, the lumen extends through the retention portion 110C.

The retention portion 110C of ureteral stent 100C includes fourextension members 114C extending from the proximal end portion 106C ofthe elongate member 102C. The extension members 114C extend in adirection away from the axis A3 defined by the elongate member 102C andinclude a proximal end 138C and a distal end 140C. The proximal end 138Cof each of the extension members 114C are coupled together, as shown inFIG. 8A.

As with the previous embodiments, the ureteral stent 100C may includeany number of extension members 114C extending from the proximal endportion 106C of elongate member 102C. For example, FIGS. 8A, 8B, and 8Call illustrate embodiments of ureteral stent 100C having four extensionmembers. FIG. 8D illustrates an embodiment of ureteral stent 100C′having three extension members. FIGS. 8E and 9B illustrate embodimentsof ureteral stent 100C″ having two extension members. In addition, theextension members may be formed in a variety of different shapes andsizes. For example, FIG. 8A illustrates an embodiment of ureteral stent100C having extension members 114C. FIGS. 8B and 8D illustrateembodiments of a ureteral stent having extension members 114C′. FIGS. 8Cand 8E illustrate further embodiments of a ureteral stent havingextension members 114C″. FIG. 9B illustrates a ureteral stent havingextension members 114C′″. The extension members 114C-114C′″ may beformed monolithically with the elongate member as described above forthe previous embodiments. Specifically, in one embodiment, the elongatemember is split to form the extension members. In addition, in oneembodiment, the extension members 114C-114C″″ are homogenouslyconstructed and have a solid cross-section as shown for extensionmembers 114C′″ in FIG. 9C. The solid cross-section extends from theproximal end to the distal end of each of the extension members114C-114C′″.

The extension members 114C′″ (114C-114C″) are configurable between aconstrained configuration, as shown in FIG. 9A, and an unconstrainedconfiguration, as shown in FIGS. 8A-8E and 9B. In the constrainedconfiguration, the proximal end portion 106C of the elongate member 102Cdefines a perimeter P2 as shown in FIG. 9D, and the extension members114C′″ collectively define a perimeter P1 as shown in FIG. 9E. Theperimeter P2 defined by the elongate member 102C is substantially thesame size as the perimeter P1 defined collectively by the extensionmembers 114C′″. In some embodiments, in the constrained configurationthe extension members 114C′″ are capable of being contained within theperimeter P2 of the elongate member 102A.

In addition, in the unconstrained configuration the extension members114C′″ (114C-114C″) are spaced apart from each other and are flexibleyet sufficiently rigid to collectively help retain at least a portion ofthe ureteral stent 100C (100C′, 100C″) within the bladder of thepatient.

CONCLUSION

While various embodiments of the invention have been described above, itshould be understood that they have been presented by way of exampleonly, and not limitation. Thus, the breadth and scope of the inventionshould not be limited by any of the above-described embodiments, butshould be defined only in accordance with the following claims and theirequivalents. While the invention has been particularly shown anddescribed with reference to specific embodiments thereof, it will beunderstood that various changes in form and details may be made.

For example, a ureteral stent according to the invention may include oneor more extension members extending from the elongate member. Theextension members may be configured in a variety of different shapes andsizes and in some embodiments include an end portion. In someembodiments, the extension members are homogenous and have a solidcross-section. In some embodiments, the extension members are formedmonolithically with the elongate member. In other embodiments, theextension members are coupled to the elongate member.

In some embodiments, the elongate member defines a lumen extending fromthe distal end portion to the proximal end portion. In otherembodiments, the elongate member does not define a lumen. In addition,in some embodiments, the extension members extend away from the axisdefined by the elongate member, in some embodiments the extensionmembers extend away from the opening defined by the elongate member andin some embodiments, the extension members extend away from both theaxis and the opening defined by the elongate member.

1. A ureteral stent, comprising: an elongate member defining an axis andhaving a proximal end portion and a distal end portion; a firstextension member extending from said proximal end portion of saidelongate member, said first extension member including a first portion,a second portion, a third portion and an end portion and having anunconstrained configuration in which said first portion is arcuate andextends away from said axis defined by said elongate member, said secondportion extends from said first portion in a distal direction, and saidthird portion extends from said second portion in a direction away fromsaid axis defined by said elongate member; and a second extension memberextending from said proximal end portion of said elongate member, saidsecond extension member including a first portion, a second portion, athird portion and an end portion and having an unconstrainedconfiguration in which said first portion is arcuate and extends awayfrom said axis defined by said elongate member, said second portionextends from said first portion in a distal direction, and said thirdportion extends from said second portion in a direction away from saidaxis defined by said elongate member, in said unconstrainedconfigurations said end portion of said first extension member and saidend portion of said second extension member are sufficiently spacedapart from each other, and said first extension member and said secondextension member are sufficiently rigid, to collectively help retain atleast a portion of the ureteral stent within a bladder of a patient. 2.The ureteral stent of claim 1, wherein said distal end portion of saidelongate member is configured to be placed in a kidney of the patient.3. The ureteral stent of claim 1, wherein in said unconstrainedconfigurations said first extension member is configured to contact abladder wall of the patient at a first contact location, said secondextension member is configured to contact the bladder wall of thepatient at a second contact location, said first contact location andsaid second contact location are disposed at a spaced distance from aureter entrance of the patient.
 4. The ureteral stent of claim 1,wherein said elongate member defines a lumen that extends from saidproximal end portion to said distal end portion of said elongate member.5. The ureteral stent of claim 1, wherein said first extension memberand said second extension member are formed monolithically with saidelongate member.
 6. The ureteral stent of claim 1, wherein said firstextension member and said second extension member are each configurablein a constrained configuration by urging said end portion of said firstextension member and said end portion of said second extension membertoward each other and in a proximal direction until said end portion ofsaid first extension member and said end portion of said secondextension member are substantially adjacent each other.
 7. The ureteralstent of claim 1, wherein said elongate member defines a lumen thatextends from said proximal end portion to said distal end portion ofsaid elongate member, said elongate member defining an opening on saidproximal end portion, said opening in communication with said lumen,said first portion of said first extension member extends in a directionaway from said opening when said first extension member is in itsunconstrained configuration, said first portion of said second extensionmember extends in a direction away from said opening when said secondextension member is in its unconstrained configuration.
 8. The ureteralstent of claim 1, wherein said elongate member defines a perimeter, saidfirst extension member and said second extension member are eachconfigurable in a constrained configuration in which said perimeterdefined by said elongate body is substantially the same size as aperimeter defined collectively by said first extension member and saidsecond extension member in said constrained configurations.
 9. Theureteral stent of claim 1, wherein said elongate member defines aperimeter, said first extension member and said second extension memberare each configurable in a constrained configuration in which said firstextension member and said second extension member are capable of beingcontained within said perimeter of said elongate member.
 10. An ureteralstent, comprising: an elongate member defining an axis and having aproximal end portion and a distal end portion; a first extension memberextending from said proximal end portion of said elongate member, saidfirst extension member having an unconstrained configuration in whichsaid first extension member has a coil configuration extending in adirection away from said axis, said coil configuration of said firstextension member including at least one complete turn, said firstextension member further including an end portion; and a secondextension member extending from said proximal end portion of saidelongate member, said second extension member having an unconstrainedconfiguration in which said first extension member has a coilconfiguration extending in a direction away from said axis, said coilconfiguration of said second extension member including at least onecomplete turn, said second extension member further including an endportion, in said unconstrained configurations said end portion of saidfirst extension member and said end portion of said second extensionmember are sufficiently spaced apart from each other, and said firstextension member and said second extension member are sufficientlyrigid, to collectively help retain at least a portion of the stentwithin a bladder of the patient.
 11. The ureteral stent of claim 10,wherein said distal end portion of said elongate member is configured tobe placed in a kidney of the patient.
 12. The ureteral stent of claim10, wherein in said unconstrained configurations said first extensionmember is configured to contact a bladder wall of the patient at a firstcontact location, said second extension member is configured to contactthe bladder wall of the patient at a second contact location, said firstcontact location and said second contact location are disposed at aspaced distance from a ureter entrance of the patient.
 13. The ureteralstent of claim 10, wherein said first extension member and said secondextension member are formed monolithically with said elongate member.14. The ureteral stent of claim 10, wherein said first extension memberand said second extension member are each configurable to a constrainedconfiguration by urging said end portion of said first extension memberand said end portion of said second extension member toward each otherand in a proximal direction until said end portion of said firstextension member and said end portion of said second extension memberare substantially adjacent each other.
 15. The ureteral stent of claim10, wherein said elongate member defines a lumen that extends from saidproximal end portion to said distal end portion of said elongate member.16. The ureteral stent of claim 10, wherein said elongate member definesa lumen that extends from said proximal end portion to said distal endportion of said elongate member, said elongate member defines an openingon said proximal end portion, said opening in communication with saidlumen, said first extension member extending in a direction away fromsaid opening when in its unconstrained configuration, said secondextension member extending in a direction away from said opening when inits unconstrained configuration.
 17. The ureteral stent of claim 10,wherein said elongate member defines a perimeter, said first extensionmember and said second extension member are each configurable in aconstrained configuration in which said first extension member and saidsecond extension member are capable of being contained within saidperimeter of said elongate member.
 18. The ureteral stent of claim 10,wherein said elongate member defines a perimeter, said first extensionmember and said second extension member are each configurable in aconstrained configuration in which said perimeter defined by saidelongate body is substantially the same size as a perimeter definedcollectively by said first extension member and said second extensionmember in said constrained configurations.
 19. A ureteral stent,comprising: an elongate member defining an axis and having a proximalend portion and a distal end portion; a first extension member extendingfrom said proximal end portion and having an unconstrained configurationin which said first extension member extends away from said axis, saidfirst extension member further including a proximal end and a distalend; and a second extension member extending from said proximal endportion and having an unconstrained configuration in which said secondextension member extends away from said axis, said second extensionmember further including a proximal end and a distal end, said proximalend of said first extension member being coupled to said proximal end ofsaid second extension member, said first extension member and saidsecond extension member each being homogenous, in said unconstrainedconfigurations said first extension member and said second extensionmember are sufficiently spaced apart from each other, and aresufficiently rigid, to collectively help retain at least a portion ofthe stent within a bladder of the patient.
 20. The ureteral stent ofclaim 19, wherein said elongate member defines a perimeter, said firstextension member and said second extension member are each configurablein a constrained configuration in which said perimeter defined by saidelongate body is substantially the same size as a perimeter definedcollectively by said first extension member and said second extensionmember in said constrained configurations.
 21. The ureteral stent ofclaim 19, wherein said elongate member defines a perimeter, said firstextension member and said second extension member are each configurablein a constrained configuration in which said first extension member andsaid second extension member are capable of being contained within saidperimeter of said elongate member.
 22. The ureteral stent of claim 19,wherein said distal end portion of said elongate member is configured tobe placed in a kidney of the patient.
 23. The ureteral stent of claim19, wherein said first extension member and said second extension memberare formed monolithically with said elongate member.
 24. The ureteralstent of claim 19, wherein said first extension member has a solidcross-section that extends from said proximal end of said firstextension member to said distal end of said first extension member andsaid second extension member has a solid cross-section that extends fromsaid proximal end of said second extension member to said distal end ofsaid second extension member.
 25. The ureteral stent of claim 19,wherein said elongate member defines a lumen that extends from saidproximal end portion to said distal end portion of said elongate member.26. The ureteral stent of claim 19, wherein said elongate member definesa lumen that extends from said proximal end portion of said elongatemember to said distal end portion of said elongate member, said elongatemember defines an opening on said proximal end portion of said elongatemember, said first extension member and said second extension membereach extending in a direction away from said opening when in saidunconstrained configurations.
 27. A method of removing a ureteral stentfrom a patient, the ureteral stent including an elongate body disposedin a ureter of the patient and a retention portion coupled to a proximalend of the elongate body and being disposed in a bladder of the patient,the retention portion having a first extension member and a secondextension member, the first extension member and the second extensionmember each having an end portion, the retention portion having anunconstrained configuration in which the first extension member and thesecond extension member each have a first portion extending proximallyin a direction away from an axis defined by the elongate body, and asecond portion extending distally, in the unconstrained configurationthe end portions of the first and second extension members are spacedfrom each other sufficiently, and the first and second extension membersare sufficiently rigid, to collectively help retain at least a portionof the ureteral stent within the bladder of the patient, comprising:urging the end portion of the first extension member and the end portionof the second extension member proximally and toward each other; andwithdrawing at least a portion of the ureteral stent from the ureter ofthe patient.
 28. The method of 27, wherein the withdrawing includesurging the ureteral stent along a guidewire.
 29. The method of claim 27,wherein the urging includes urging the end portion of the firstextension member and the end portion of the second extension memberproximally and toward each other simultaneously.